Incandescent lamp and the like and method of making same



I Oct. 14, 1941. s. KARASICK INCANDESCENT LAMP AND THE LIKE AND METHOD OF MAKING SAME Filed March 15, 1937 2 Sheets-Sheet l INVENTOR. SAMUEL Kazmszcx ATTORNEY.

Oct. 14, 1941. KARASICK INCANDESCENT LAMP AND THE LIKE AND METHOD OF MAKING SAME Filed March 15, 1937 2- Sheets-Sheet 2 INVENTOR. SAMUEL K'ARAsmK ATTORNEY.

Patented Oct. 14, 1941 UNITED STATES PATENT OFFICE INCANDESCENT LAMP AND THE AND METHOD OF MAKING SAME Samuel Karasick, Mount Vernon, N. Y. Application March 13, 1937, Serial No. 130,707

' 4 Claims.

This invention relates to incandescent lamps,

thermionic tubes and the like, as well asto the method of making the same.

In former devices of this type it has been the practice to mount the filament or other electrodes of such devices on a glass press or support within anvevacuated envelope. Thereafter, a socket engaging base is attached to the envelope and the external leads of the filament or other electrodes are soldered to contacts mounted on the base.

In accordance with the main features of the invention, it is proposed to obviate the need of a separate base for a lamp or like device by forming socket engaging parts on an integral portion. of the glass envelope.

An additional feature of the invention relates to the novel arrangement of parts of an incan-.

descent lamp or the like whereby the separate operations of exhausting the envelope and sealing-in the lead wires can be combined in one operation.

A further feature of the invention relates to l the method of assembling the various parts of an incandescent lamp or similar device such as a thermionic tube, in a vacuum whereby the socalled tipping off operation on the exhaust tube of the device is eliminated and evacuation of the device is effected with much greater dispatch.

Still another feature of the invention relates to the method of forming the base of an incandescent lamp or like device whereby the reentrant stem portion of former devices can be e1im-' inated.

Various other features and advantages of the invention will appear from the detailed figures and claims when taken with the drawings in which- 1 1:

Fig. 1 is a vertical section taken major axis of an incandescent lamp, made in accordance with this invention.

Fig. 2 is a horizontal section taken along lines 2-2 of Fig. 1.

. along the 1 mately equal to that of glass.

Fig. 8 is a vertical section taken on the major axis of a still further modified lamp, and

Fig. 9 is a vertical section of an apparatus for;

evacuating and sealing in the filament of a: lamp of the form shown in Fig. 8.

Referring to Fig. 1, reference character I indicates generally an incandescent lamp made in accordance with this invention. The lamp comprises an, enlarged thin glass-walled bulb portion 2 to envelop the filament 3 therein. The bulb portion 2 merges into a neck portion 4 which terminates in an. integral base portion 5. As

' shown in Fig. 2, the base portion is cross-shaped,

that is, it has four projecting portions 6, l, 8 and 9. The outer edges IU of the portions 6, I, 8 and 9 are each formed with sloping parallel grooves ll thereon which are in reality portions or segments of a spiral groove or thread whereby the base maybe screwed into a conventional light socket. The lateral surface of the base has thereon a metallic coating C of copper, aluminum or other electrical conductin material, which may be applied either by spraying, utilizing any of the well known processes for this, or by evaporation and condensation in vacuo. The filament 3 is supported within the bulb portion 2 by means of a pair of stiff lead wires i2 and 13 having their lower portions sealed within the base, preferably in the opposing portions 6 and 8 thereof. It is to be understood that the sections l4 and I5, of the lead wires which are sealed within the glass base are made of conducting material, such as dumet wire, having a coeflicient of expansion approxi- The' lead wires l2 and I3 adjacent the filament 3, are tied together by means of a glass bead i6. Since no reentrant tube or support is used with the lead wires, a perforated mica disk I! may be'used to aid-in supporting the lead wires. There extends axially through the base 5 an exhaust channel I 8 which communicates with the exhaust tube IS. The, interior of the lamp may be exhausted in the usual manner and the tip 20 of the exhaust tube I9 is thereafter sealed.

During the forming of the base 5 into the cross section shown in Fig. 2, the lead wires [2 and I3 are sealed therein and the exhaust channel I8 is kept open by means of a suitably shaped plug of refractory material, such as graphite (not shown). The base 5 is formed principally from the bulb neck but during the forming operation additional glass may be fused in as required. The sealed end 20 of the exhaust tube I9 is covered and protected by a metal cap 2| which may be suitably secured thereover, as by means of cement 22. 'The lead wire I2 is soldered or otherwise suitably secured to. the cap member 2| as at 23, while the second-lead wire I3 is soldered or. otherwise suitably secured to the metallic coating as at 24. The joint 24 is preferably located within the recess formed between the adjacent projecting portions of the base so that the irregularity'of the surface caused by this joint does not interfere with the engagement of the screw thread segments II with the screw threads of a light socket. In order to prevent accidental short circuiting of the cap member 2| and the lead wire l3, an insulating washer 25, such as Bakelite, may be interposed between the cap 2| and.the external portion of the lead wire [3.

Referring'now to the modification illustrated in Figs. 3 and 4 there is herein illustrated a lamp similar in form to that disclosed in Figs 1 and 2.

- However, the exhaust channel and tube are elimi-' nated. This lamp 30 comprises a thin walled glass bulb portion or'envelope 3| which merges into a reduced neck portion 32, the lower end of'which is formed into a solid base portion 33. There extends axially through the base and sealedtherein, the central lead wire 34 while a second lead wire 35 is also sealed within the base but in'oflset relation to the lead wire 34. It is, of course, understood that the portions .of the lead wire which are sealed within the base may be of "Dumet" wire. The upper ends of the lead wires 34 and 35 support a filament 35 within the bulb portion 3| of the lamp. As shown lamp bulb 30 is additionally supported by means of the annular tapered rubber gasket member 53 which seals the interior of the bulb 30 from the the annular ring 5|.

35 carrying the filament 36 are supported on the in Fig. 4, the outline of the base 33'is crossshaped as in the case of the lamp l. The outer-' most edges 31, 38, 39 and 480i the base are grooved similarly to the base 5 oflamp I illus trated in Figs. 1 and 2. the lateral walls of the base portion being coated with a metallic layer chamber formed by the cup 49. By applying suitable suction means to the pipe 45, the interior of the bulb may thus be evacuated to an absolute pressure of a micron of mercury or less, while the space within the cup 48 but outside of the lamp 30 may be evacuated through the exhaust pipe to an absolute pressure of one millimeter of mercury or less. Electrically heated base forming dies 54, preferably four in number are supported within the cup. The surfaces of these dies correspond to the desired external surface of the base of the finished bulb, e. g. that illustrated in Figs. 3 and 4. The lower ends of the dies are substantially flush with the upper surface of the poppet shaped member 48 so that as the dies are moved inwardly toward the bulb, the excess glass will be sheared from the bulb proper.

In forming the bulb such as shown in Figs. 3

and 4 with the apparatus illustrated in Fig. 5 the following procedure may be followed: A lamp-bulb of the form shown at 38 in Fig. 5 is placed on the rubber member 53 and held upright by means of Suitable lead wires 34 and poppet-shaped member 41 by extending the lower ends of these wires into the apertures 48 therein. The base forming dies 54 are heated by means of the electrical resistance units 55 carried therein. The interior of the bulb is evacuated, through the pipe 45 to an absolute pressure of a micron of mercury or less and the chamber surrounding the bulb is evacuated through the pipe 45 to an absolute pressure of a millimeter or less whereby the bulb when heated, will not be distorted as would result if wide difference in pressure existed between the inner and outer bulb surfaces. When the dies 54 have reached such temperature as to soften the glass, they are simultaneously moved \inwardly (by means not shown) thereby forming the neck portion of the lamp into the shape shown in cross section in Fig. 4. The means for supterfere with the introduction of the lamp base into a lamp socket. The central lead wire is secured as by soldering, to a metallic cap member 43, cemented or otherwise suitably secured centrally of the outer end of the base 33. As in the case ofthe lamp 1, an insulating washer, similar to the washer 25, may be secured to the base 33.

In Figs. 5 and 6 there is illustrated an appa- I ratus for evacuating, for sealing-in the filament and the stiif lead wire supports and for forming the base portion of a lamp such as shown in Figs. 3 and 4. The apparatus comprises a supporting plate 44 provided with two exhaust pipes 45 and 48, the exhaust pipe 45 being located centrally of the plate 44. There projects upwardly from the plate 44 and along the axis of the exhaust pipe 45, the member 41 which has the appearance of a poppet valve. The member 41 is rigidly held in position by means of the block secured to the member 41 and welded or otherwise suitably fas-' tened to the wall ,of the pipe 45. The member 41 is provided with a pair of holes 48 to receive lead wires. An inverted cup 48 rests on the base while a gasket 58 provides an air tight seal between the cup 40- and the plate 44. The. lamp bulb 38 is supp rted in the position shown in Fig. 5 by means of an annular ring5| which may be manipulated by means of a push rod 52 porting and moving the dies 54 have been omitted for the sake of clearness. However, many means for shifting the dies will occur to those skilled in the art. For example, the dies can be provided with apparatus similar to the levers 81 and ring 35 shown in Fig. 9 for moving the 'wedges 82 except that the lower ends 98 of the levers would engage the lower edge of the ring instead of the upper edge as shown in Fig. 9 or the lower ends 98 may extend through slots formed in the ring 95 to obtain a positive reciprocation of dies 'hinged to the upper end of the levers. As'the base is formed, the lead wires are also sealed in the base, and the excess glass bee low-the base proper is sheared 01! by the coaction' of the lower surfaces of the dies and the upper surfaces of the-poppet shaped member 41. Since apparatus of Fig. 5 and the metallic coating 4| is then applied inlthe manner hereinbefore described. The lead wire 35 is soldered to the coating 4|. The central lead wire is soldered to I the metal'cap 43 to complete the lamp.

In Fig. '1 there is illustrated afurther modification of applicants invention. The lamp hereextending through the plate 44.- The neck 01. the 15 in illustrated is similar to the lamp previously ference between the lamp illustrated in Fig. 7 a

' and that illustrated in Fig. 3 is that a central integral glass tube 62, carried by the base, is provided within the lamp. Reference character 56 indicates the lamp generally which comprises a bulb portion 51 and a neck portion 58 merging into a solid base portion 59. The base portion 59 in horizontal section has the same appearance as lamp 30 and as shown in Fig. 4. The cross shaped base 59 has grooves 60 formed in the outer edges of the projecting portions thereof as in the case of lamps I and 39 illustrated in Figs. 1 and 3. The lateral surface of the base is provided with a metallic coating 6| as in lamps I and 30. A glass tube 62 is disposed axially within the bulb which tube at its lower end is fused integrally with'the base. The upper end of tube 62 is flared and the flared portion 63 has fused therein a plurality of filament supporting hooks 64. A filament 65 is carried by said hooks. A central lead wire 66 extends through the bore of said tube '62, the upper end of which wire is secured to one endof the filament. The other end of the filament is secured to a. second lead wire 61 which is positioned outside of the tube 62. The lower end ofthe central lead wire 66 is sealed in the central portion of the base and prcjectstherefrom and is secured to a metal cap 67 cemented to the lower surface of the base. The second lead wire 61 is also sealed in the base and projects therebelow and is soldered or otherwise suitably joined to the metallic coating 6E. The bulb 56 may be formed on an apparatus similar to that shown in Figs. 5 and 6 wherein the lead wires and tube 62 carrying the filament thereon will be fuzed into the base portion-by means of electrically heated dies, the tube and lead wires being supported by the member ll during the forming operation. An insulating washer may be applied to the base 59 in the same manner as washer shown in Fig. 1.

From the above description it will be seen that the filament supports and leading-in wires I2 and I8, 39 and 35, and 66 and 61 of the lamps i, 39 and 56 respectively are sealed in their respective bases by softening the glass which is to constitute the finished base and pressing this softened glass into sealing engagement with the leading-in wires. In the claims the term press seal" is used to indicate the portion of a lamp having leading-in wires sealed therein in this manner.

The lamp I9 illustrated in Fig. 8 comprises a bulb portion H, a neck portion 12 integral therewith and terminating screw-threaded base portion 13. There is-sealed within the closed end of the base portion 13, a central lead wire 14 which at its lower end is secured to a metal cap 15 cemented or otherwise suitably secured to the center of the lower surfaceof the base. Offset from the central lead wire it is a second lead wire 16 which is also sealed into the base and has aprojecting portion 11 which is soldered to the metallic coating 18 on the screw threaded portion of the base. The upper ends of the lead wires M and 16 which are disposed within the bulb ll carry a suitable filament I9 either of the coiled type or the coiled-coil type. The lead wires are maintained in spaced relation by means of a glass head 89 secured thereon. An insulating washer may be applied to the base 19 if desired, as previously described.

It will be understood that each type of lamp herein disclosed may be 'filled with nitrogen or like gas after the lamp has been evacuated but before it is sealed. H

In evacuating and sealing the lamp I0, an apparatus as illustrated in Fig. 9 may be used. This apparatus comprises a plate 8| provided with a detachable chamber-forming cap 82 which is sealed to the base by means of a gasket 83. An exhaust pipe 84 extends through the central portion of the plate and communicates with the chamber formed by the cup and the plate. An

annular member 85 perforated as at 86, rests on the base. The upper end of the annular member 85 is formed of refractory material 81 and carries an annular electrical heating element 88. This heating unit engages the flange 89 of the lower section of a bulb. The lower section of the bulb supported on the heating element 88 comprises a preformed bulb section having integral therewith'a screw threaded base portion which carries therein the lead wires and filament. The upper section of the bulb portion has a rim 99 which is engaged by an annular electrical heating unit 9|. The upper and lower sections of the lamp are maintained in spaced relation by means of the wedges 92. A push rod 93 extends through the air tight seal 94 formed in the plate BI and carries at its upper end an annular ring 95. There is pivotally mounted at 96 on the annular member 85, the levers 91, the lower ends of which are formed with cam surfaces 98 adapted to be engaged by the annular ring 95. The upper ends of these levers 97 are pivotally secured to the sliding wedges 92.

After the parts have been assembled as shown in Fig. 9, the flanges 89 and 99 of the two bulb sections are heated by means of the electrical heating units 86 and 9i and at the same time the chamber and the interior of the bulb sections are evacuated by suitable suction means effective through the exhaust pipe 84. After the evacuation has been completed, nitrogen or other like gas may be introduced. Thereafter when the flanges 89 and 99 have been softened by heat to the point where they will fuse upon contact, the push rod 93 is raised causing the lower ends 98 of the levers 91 to swing inwardly about the pivots 96 as the cam surfaces 98 of these levers move along the annular ring 95. As the lower ends of the levers 9! swing inwardly, the upper ends of the levers and the wedges 92 pivotally secured thereto will move outwardly and the upper section of the lamp bulb will drop down into contact with the lower section of the bulb. The glass flanges 89 and 90 having been softened by heat, will fuse together.

While this invention has been described particularly with reference to incandescent lamps made entirely of glass, it should be understood that it is not'to be thus'limited, since it is applicable to thermionic or vacuum tube devices, wherein the electrodes thereof are supported on a molded lower glass section, to the upper part or edge of which a dome-like section is sealed.

This sealing operation may be performed in a high vacuum, as in the case of the lamps disclosed in Figs. 3 and 4. Furthermore, it is within the scope of this invention to make composite metal and glass envelopes for such devices,

wherein the dome-like section is of metal, by us ing metal to glass seals. Such seals can be made by utilizing either the Fernico alloy or the Housekeeper type of metal-glass seal, said seals being formed in an evacuated vessel, since by this method the necessity of a separate exhaust 4 t I i As" is well known intheart, the-space within each of the sealed envelopes or bulbs described above is either evac'uated or filled with a gas that will not accelerate the deterioration of the electrode or'electrodes when in use. In the claims the word "medium has been used to indicate either the presence of such a gas or a vacuum, each having the characteristic of not accelerating the deterioration of the electrode or electrodes.

Some of the principal advantages of the constructions and exhaust methods herein disclosed are: The elimination of a separate exhaust and seal-in process, the two being combined; the elimination of the tipping off operation on the exhaust tube which now limits the speed of production as this operation cannot be carried out rapidly; the improved exhaust over that now attainable due to the definite low limit of attainable exhaust speed and vacuum with a small exhaust tube as now required; the elimination of the base as a separate element in lamp or discharge device assembly; the elimination of the reentrant stem and its manufacture as separate steps.

What I claim is: r

1. The method of forming a lamp which method comprises supporting a bulb-like envelope within a chamber, supporting lead wires and a filament carried thereby within said envelope, evacuating the interior of said envelope, evacuating the space within the chamber exteriorly of the envelope, pressing heated dies against a portion of said envelope to seal said lead wires therein and simultaneously from a socket engaging portion thereon.

2. A stage in the method of making a lamp including an envelope having a filament or electrodes enclosed therein, said filament or electrodes being provided with leads which stage comprises evacuating said envelope in an evacuated chamber, heating a portion of said envelope, pressing the heated material of the envelope about portions of said filament or electrode leads to form an air tight seal and simultaneously form a socket-engaging portion on said envelope, the pressures within said chamber and said en.- velope being such' that a negligible deformation of the envelope will result.

3. A stage in the method of working and shaping an evacuated envelope which stage comprises heating a portion of said envelope by means of heated elements in an evacuated vchamber. and utilizing said elements to seal said envelope while simultaneously forming a socket engaging base thereon in said evacuated chamber.

4. The method of making a sealed evacuated envelope, which method comprises heating a portion of said envelope in an evacuated container,

and pressing said heated portion of the envelope to-seal said envelope and form a socket-engaging portion thereon while said envelope is in said 

